Atomizer

ABSTRACT

An atomizer includes a piezoelectric element  50  with comb-type electrodes having one electrode and the other electrode formed alternately at one side, a mesh member  40  having many small holes arranged in the proximity of a no-electrode formation plane of piezoelectric element  50,  a liquid reagent bottle  20  storing a liquid L, and a solenoid  26  supplying the liquid L of liquid reagent bottle  20  between piezoelectric element  50  and mesh member  40.  The vibratory wave of piezoelectric element  50  by an oscillation circuit is a bulk wave that travels within the piezoelectric element, not the surface wave propagating at the surface of the piezoelectric element defined by the comb-type electrode pitch. As a result, an atomizer can be provided improved in atomization efficiency and stabilized in atomization.

TECHNICAL FIELD

The present invention relates to an atomizer that sprays out liquidutilizing a piezoelectric element.

BACKGROUND ART

An atomizer of interest to the present invention is disclosed in, forexample, International Publication Nos. WO93/20949 and WO97/05960. Theconventional atomizer disclosed in these publications has a metal horncombined with a mesh member with many small holes to spray out liquid atlow power consumption. In this atomizer, one end of the metal horn isimmersed in the liquid in a reservoir. The mesh member is arranged atthe other end of the metal horn. By the ultrasonic-vibration of theultrasonic vibrator attached to the metal horn, liquid is absorbed fromone end of the metal horn. The absorbed liquid is atomized by thesynergistic effect between the metal horn that is vibratedultrasonically and the mesh member.

However, such an atomizer has problems such as: {circumflex over (1)}positioning between the mesh member and metal horn; and {circumflex over(2)} stability of atomization. As to problem {circumflex over (1)}, theatomization action will become insufficient if the distance between themesh member and the other end of the metal horn is too large or toosmall to degrade the atomization efficiency. As to problem {circumflexover (2)}, the structural distance between the mesh member and the metalhorn is apt to become unstable to result in an unconstant atomizationaction. There was a problem that stable atomization is difficult.

DISCLOSURE OF THE INVENTION

In view of the foregoing, one object of the present invention is toprovide an atomizer of favorable atomization efficiency.

Another object of the present invention is to provide an atomizer thatcan effect atomization stably.

In order to achieve the above objects, an atomizer of the presentinvention includes a piezoelectric element with comb-type electrodeshaving one electrode and the other electrode formed alternately, anoscillator to drive the piezoelectric element, a mesh member having manysmall holes arranged in close proximity to the piezoelectric element, areservoir storing a liquid, and a liquid supply device supplying theliquid in the reservoir between the piezoelectric element and the meshmember. The vibratory wave used in the atomization of the piezoelectricelement by the oscillator is a wave that travels mainly through thepiezoelectric element (bulk wave).

In this atomizer, the piezoelectric element with comb-type electrodeshaving electrodes formed alternately are combined with a mesh member anduses the bulk wave that travels through the piezoelectric element.Therefore, a great oscillatory displacement is obtained with a smallelectrical energy. The atomization efficiency is favorable.

Preferably, the material of the piezoelectric element is lithium niobatewith a 41±15° rotation Y cut and Y axis projection propagationdirection. The oscillation efficiency is improved by the usage of apredetermined propagation direction of the material.

Preferably, the piezoelectric element has a thickness so that theoscillation frequency of the surface wave and the oscillation frequencyof the bulk wave differ from each other. The comb-type electrode of thepiezoelectric element is arranged so that the oscillation frequency ofthe surface wave differs from the oscillation frequency of the bulkwave. As a result, the oscillation frequency of the bulk wave isstabilized without rendering the oscillation circuit complicated.

Preferably, at least the end portion of the piezoelectric elementcrossing the advancing direction of the surface wave has a configurationso that the wave reflected at that end does not interfere with thesurface wave. As a result, no interference of the vibratory wave(surface wave or bulk wave) occurs. Oscillation is stabilized.

Preferably, the piezoelectric element has two opposite planes. Thecomb-type electrode is provided only at one plane side of thepiezoelectric element, opposite to the plane facing the mesh member.Since the comb-type electrode does not come into contact with theliquid( liquid reagent), electrode corrosion, electrical corrosion andelectrical shorting by the liquid reagent can be prevented.

According to another aspect of the present invention, an atomizerincludes a piezoelectric element with comb-type electrodes having oneelectrode and the other electrode formed alternately, an oscillatordriving the piezoelectric element, a mesh member having many small holesarranged in close proximity to the piezoelectric element, a reservoirstoring a liquid, and a liquid supply device supplying the liquid in thereservoir between the piezoelectric element and the mesh member. Themesh member is of a horn configuration in which the cross sectionalshape of the small hole is defined according to the oscillationfrequency of the piezoelectric element and the sound speed of the fluid.Since the cross sectional shape of the small hole of the mesh member isof a horn configuration that is defined according to the oscillationfrequency of the piezoelectric element and the sound speed of the fluid,atomization of favorable efficiency can be achieved with a relativelysmall power.

According to a further aspect of the present invention, an atomizerincludes a piezoelectric element with comb-type electrodes having oneelectrode and the other electrode formed alternately, an oscillatordriving the piezoelectric element, a mesh member having many small holesarranged in close proximity to the piezoelectric element, a reservoirstoring a liquid, and a liquid supply device supplying the liquid in thereservoir between the piezoelectric element and the mesh member. Thepiezoelectric element and the mesh member are arranged so that theplanes facing each other cross at an acute angle. The liquid from theliquid supply device is provided from the opening side therebetween.

Also, there are provided a piezoelectric element with comb-typeelectrodes having one electrode and the other electrode formedalternately, an oscillator driving this piezoelectric element, a meshmember having a plurality of small holes arranged in close proximity tothe piezoelectric element, a reservoir storing a liquid, and a liquidsupply device supplying the liquid in the reservoir between thepiezoelectric element and the mesh member. The piezoelectric element andthe mesh member are arranged to have their facing planes cross eachother at an acute angle. The reservoir includes a supply pipe extendingto the opening side between the piezoelectric element and the meshmember.

As a result, the remaining amount of liquid in the reservoir can beminimized. Also, atomization is allowed of a liquid of low viscositysuch as an agent dissolved with alcohol or a liquid of low surfacetension including a surfactant.

According to still another aspect of the present invention, an atomizerincludes a piezoelectric element with comb-type electrodes having oneelectrode and the other electrode formed alternately, an oscillatordriving the piezoelectric element, a mesh member having many small holesarranged in close proximity to the piezoelectric element, a reservoirstoring a liquid, and a liquid supply device supplying the liquid in thereservoir between the piezoelectric element and the mesh member. Thepiezoelectric element is characterized in that the circumferential endportion is pressed and fittedly held by waterproof packing. As a result,water resistance can be improved while minimizing the oscillatoryattenuation of the piezoelectric element.

According to a still further aspect of the present invention, anatomizer includes a piezoelectric element with comb-type electrodeshaving one electrode and the other electrode formed alternately, anoscillator driving this piezoelectric element, a mesh member having manysmall holes arranged in close proximity to the piezoelectric element, areservoir storing a liquid, and a liquid supply device supplying theliquid in the reservoir between the piezoelectric element and the meshmember. The piezoelectric element has a liquid sense electrode sensingthe liquid from the reservoir at the comb-type electrode formationplane. A liquid sense circuit substrate is provided sensing whetherthere is a liquid or not according to the signal from the liquid senseelectrode. The liquid sense circuit substrate is arranged below thecomb-type electrode formation plane of the piezoelectric element. Theliquid sense electrode of the piezoelectric element and the liquid sensecircuit substrate are electrically connected by a conductive resilientbody.

As a result, the distance between the liquid sense electrode of thepiezoelectric element and the liquid sense circuit substrate can beminimized to reduce the influence of disturbance noise. Also, theelectrostatic capacity at the electrical connection between the liquidsense electrode and the liquid sense circuit substrate can be reduced toimprove the S/N. Furthermore, the contact reliability between the liquidsense electrode and the liquid sense circuit substrate can be ensuredwhile minimizing the oscillation attenuation caused by electricalcontact.

According to yet a further aspect of the present invention, an atomizerincludes a piezoelectric element with comb-type electrodes having oneelectrode and the other electrode formed alternately, an oscillatordriving this piezoelectric element, a mesh member having many smallholes arranged in close proximity to the piezoelectric element, areservoir storing a liquid, and a liquid supply device supplying theliquid in the reservoir between the piezoelectric element and the meshmember. The liquid supply means is characterized in supplying the liquidin the reservoir by the press-operation of a diaphragm.

Also, an atomizer includes a piezoelectric element with comb-typeelectrodes having one electrode and the other electrode formedalternately, an oscillator driving this piezoelectric element, a meshmember having many small holes arranged in close proximity to thepiezoelectric element, a reservoir storing a liquid, a liquid supplydevice supplying the liquid in the reservoir between the piezoelectricelement and the mesh member, and a liquid amount sensor sensing theamount of liquid on the piezoelectric element. The liquid supply devicesupplies the liquid in the reservoir by press-operation of a diaphragm.The press-operation of the diaphragm is controlled according to theoutput of the liquid amount sensor.

As a result, the liquid of an optimum amount can be supplied to solveany inconvenience such as supply clogging or the like.

According to yet another aspect of the present invention, an atomizerincludes a piezoelectric element with comb-type electrodes having oneelectrode and the other electrode formed alternately, an oscillatordriving this piezoelectric element, a mesh member having many smallholes arranged in close proximity to the piezoelectric element, areservoir storing a liquid, a liquid supply device supplying the liquidin the reservoir between the piezoelectric element and the mesh member,and a mesh member case holding the mesh member. The mesh member case isformed of metal or ceramic.

As a result, the absorption of the oscillation energy that propagatesthrough the liquid can be suppressed to improve the atomizationefficiency. Also, the shock strength with respect to impact such as whendropping the apparatus is increased. An atomizer with a mesh member casethat is not easily damaged can be provided.

According to yet a still further aspect of the present invention, anatomizer includes a main unit, a main unit cover attached removably tothe main unit, a piezoelectric element, an oscillator driving thispiezoelectric element, a mesh member having many small holes arranged inclose proximity to the piezoelectric element, a reservoir storing aliquid, and a liquid supply device supplying the liquid in the reservoirbetween the piezoelectric element and the mesh member. The oscillator isarranged at the main unit whereas the piezoelectric element, the meshmember, the reservoir, and the liquid supply device are arranged at themain unit cover.

Since the piezoelectric element, the mesh member, the reservoir and theliquid supply device are arranged at the main unit cover in theatomizer, the maintenance is facilitated by removing the main unit coverfrom the main unit with the components as modular components. Assemblyis facilitated. Particularly the main unit cover or the circuitsubstrate arranged within the main unit, when damaged, can be replacedeasily. As to the atomization mechanism portion at the part of the mainunit cover that requires critical adjustment, the accuracy can bemaintained by providing the same as modular components that cannot beeasily detached.

According to yet a still further aspect of the present invention, anatomizer includes, at a main unit, a piezoelectric element, anoscillator driving this piezoelectric element, a mesh member having manysmall holes arranged in close proximity to the piezoelectric element, areservoir storing a liquid, and a liquid supply device supplying theliquid in the reservoir between the piezoelectric element and the meshmember. An operation display and a voltage monitor display are providedat the upper portion of the main unit. These displays are arranged so asto allow visual confirmation in a direction substantially identical tothe spray out direction from the main unit.

Since the operation display and the voltage monitor display can beeasily visualized during inhalation of the spray, confirmation of theconductive state during inhalation and confirmation of the warningdisplay when the battery is low can be carried out easily in theinhalation posture.

According to an additional aspect of the present invention, an atomizerincludes, at a prismatic main unit, a piezoelectric element, anoscillator driving this piezoelectric element, a mesh member having manysmall holes arranged in close proximity to the piezoelectric element, areservoir storing a liquid, and a liquid supply device supplying theliquid in the reservoir between the piezoelectric element and the meshmember. The main unit includes a projection protruding backwards at therear of the upper portion, an atomize unit at the upper portion, and anoperation switch at the front of the upper portion corresponding to theprojection.

According to the present atomizer, the operation switch can be operatedwhile holding the main unit with a natural grip. The possibility ofdropping the apparatus erroneously during operation is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an atomizer according to an embodiment of thepresent invention.

FIG. 2 is a side view of an atomizer with the cover removed from themain unit case.

FIG. 3 is a front view of the atomizer of FIG. 2.

FIG. 4 is a top view of the atomizer of FIG. 2.

FIG. 5 is a sectional view of the main part of the atomizer.

FIGS. 6A and 6B are sectional views in a partially broken away form ofan atomizer with the cover removed from the main unit case.

FIGS. 7A and 7B are a top view and a side view, respectively, of themain unit cover of an atomizer.

FIGS. 8A and 8B are a right side view and a left side view,respectively, of the main unit cover of FIGS. 7A and 7B.

FIG. 9 is a top view showing the interior of the main unit cover ofFIGS. 7A and 7B.

FIG. 10 is an enlarged view of a solenoid used in an atomizer.

FIGS. 11A and 11B are a top view and a side view, respectively, of anatomize unit at a main unit cover of an atomizer.

FIGS. 12A and 12B are a cross sectional view and a top view,respectively, of the interior of the atomize unit shown in FIGS. 11A and11B.

FIG. 13 is an enlarged sectional view of the main part of a main unitcover of an atomizer.

FIG. 14 is a diagram describing atomization at the main unit cover ofthe atomizer.

FIG. 15 is a perspective view of a piezoelectric element and a liquidsensor circuit substrate used in an atomizer.

FIG. 16 is a perspective view showing a piezoelectric element used in anatomizer.

FIG. 17 is a diagram describing the vibration principle of apiezoelectric element used in an atomizer.

FIGS. 18A, 18B and 18C show examples of the configuration of ano-electrode formation portion of a piezoelectric element used in anatomizer.

FIGS. 19A, 19B and 19C show an example of the end configuration of ano-electrode formation portion of a piezoelectric element used in anatomization device.

FIG. 20 is a side view showing the case where comb-like electrodes areprovided at both sides of a piezoelectric element.

FIG. 21 is an enlarged sectional view of the main part describingatomization of an atomizer.

FIGS. 22A and 22B show the case where the mesh cross sectionconfiguration is of a conical type and an exponential type.

BEST MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described hereinafter withreference to the drawings.

Referring to FIGS. 1 and 2, an atomizer according to the presentembodiment includes a prismatic main unit case (main unit) 1, and acover 2 attached removably to main unit case 1. Main unit case 1includes a projection la protruding backwards at the back side of theupper portion, and an operation switch 9 for turning ON/OFF the power atthe front face of the upper portion corresponding to projection 1 a.

Referring to FIGS. 4-9, a main unit cover 10 appears at the upperportion of main unit case when cover 2 is removed from main unit case 1.Main unit cover 10 is detachable with respect to main unit case 1. Apiezoelectric element 50, a mesh member 40, a reservoir, and a liquidsupply unit that will be described afterwards are arranged at main unitcover 10.

Main unit cover 10 includes a liquid reagent bottle (reservoir) 20storing a liquid (for example, liquid reagent). Liquid reagent bottle 20is formed of an upper part 21 and a lower part 22. Lower and upper parts21 and 22 are fitted to each other. A cap 23 that seals a liquid reagentinlet 21 a that can be opened/closed is attached to upper part 21.Liquid reagent can be introduced into liquid reagent bottle 21 fromliquid reagent inlet 21 a by opening cap 23. A diaphragm 24 is attachedat the bottom of liquid reagent bottle 20 (lower part 22). A liquidsupply pipe 25 is attached at the slanting lower side of lower part 22.The liquid reagent is arbitrary. In the atomizer of the presentinvention, a liquid of low viscosity such as chemicals dissolved inalcohol or a liquid of low surface tension including a surfactant can besprayed out.

A solenoid 26 is provided at the lower portion of liquid reagent bottle20 to urge diaphragm 24 to supply a liquid. As shown in FIG. 10,solenoid 26 is attached to a solenoid holder 28 where a solenoid shaft26 a pushes a pin 27. Pin 27 is in contact with diaphragm 24 in thenormal state. Upon actuation of solenoid 26, solenoid shaft 26 a pushespin 27, which in turn urges diaphragm 24. As a result, the liquid inliquid reagent bottle 20 is appropriately discharged through liquidsupply pipe 25.

According to this liquid reagent supply structure, an optimum amount ofliquid reagent can be supplied by appropriately setting the displacementof diaphragm 24 caused by the urge of pin 27. Thus, inconvenience suchas supply clogging can be prevented. Conventionally, the liquid wassupplied taking advantage of the weight of the liquid reagent itself orthe capillary phenomenon through a thin pipe from the liquid reagenttank. There was the inconvenience that, depending upon the concentrationand status of the liquid reagent, an appropriate amount could not besupplied or supply clogging occurred.

As an alternative to solenoid 26, pin 27 can be operated using a motor,or pin 27 can be operated by air pressure.

An atomize unit 30 is provided at the lower part 22 of liquid reagentbottle 20. Atomize unit 30 has a structure as shown in FIG. 11A (topview), FIG. 11B (side view), FIG. 12A (sectional view) and FIG. 12B (topview with upper case removed). Atomize unit 30 includes an upper case 31and a lower case 32 which are fitted to each other. A mesh member caseis formed by upper and lower cases 31 and 32. At lower case 32 areprovided a mesh member 40 with many small holes and a coil spring 34urging mesh member 40 against lower case 32. Spring 34 has one endengaged with upper case 31 and the other end engaged with the perimeterof mesh member 40. Accordingly, mesh member 40 is held constantly, urgedagainst lower case 32.

Mesh member 40 is formed of metal or ceramic in order to suppress theabsorption of oscillation energy conveyed to the liquid reagent toimprove the atomization efficiency and increase the shock strength whenmain unit cover 10 is dropped. More specifically, the liquid reagent isin contact with mesh member 40 during atomization and also in contactwith the mesh member case (upper and lower cases 31 and 32) holding meshmember 40 at the same time. Conventionally, the mesh member case isformed of resin, so that the vibration of the liquid reagent and themesh member will be attenuated by the resin mesh member case. By formingthe mesh member case of metal or ceramic as in the present invention,such problems can be eliminated.

As shown by the enlarged sectional view of the main part of FIG. 13, apiezoelectric element 50 is positioned in an oblique manner in closeproximity at the lower portion of mesh member 40 positioned oblique withrespect to the horizontal plane. Mesh member 40 and piezoelectricelement 50 have their facing planes cross each other at an acute angleto have liquid reagent L from liquid supply pipe 25 supplied from theopen side therebetween. By the above structure, the remaining amount ofliquid reagent L in liquid reagent bottle 20 can be minimized. Also, aliquid of low viscosity can be atomized. When the remaining amount ofliquid reagent L in liquid reagent bottle 20 becomes low so that liquidL supplied from liquid supply pipe 25 is reduced, liquid reagent L willbe atomized by the surface tension with mesh member 40 up to the lastdrop, as shown in FIG. 14. Liquid reagent L can be used for spray outwith no waste.

Although not shown in the drawing, a liquid amount sensor that sensesthe amount of liquid reagent on piezoelectric element 50 can be providedto control the urge operation of diaphragm 24 according to the output ofthis liquid amount sensor.

As shown in FIGS. 15 and 16, piezoelectric element 50 includes comb-typeelectrodes having one electrode 51 and the other electrode 52 formedalternately at one plane, and liquid sense electrodes 55, 56 formed onthe same plane and at a position in contact with the liquid reagentsupplied from liquid supply pipe 25. Piezoelectric element 50 isarranged so that the plane (no-electrode formation plane) opposite tothe plane where electrodes 51, 52, 55 and 56 are formed faces meshmember 40. This is because the vibratory wave of piezoelectric element50 used for atomization is a bulk wave 61 traveling therethrough, notthe conventional surface wave 60. By arranging the no-electrodeformation plane of piezoelectric element 50 so as to face mesh member40, the electrodes will not come into contact with the liquid reagent.The apparatus can be protected from electrode corrosion, electriccorrosion and electrical shorting caused by the liquid reagent. Thus,reliability is improved.

Although not particularly limited, the material of piezoelectric element50 is preferably lithium niobate with a 41±15° rotation Y cut and a Yaxis projection propagation direction from the standpoint of utilizing abulk wave as an vibratory wave.

Although not depicted in the drawing, piezoelectric element 50 has itscircumferential end portion pressed and fitted by waterproof packing. Inpiezoelectric element 50, the comb portion where comb-type electrodes 51and 52 are formed oscillates. The oscillation of the circumferential endportion of piezoelectric element 50 is smaller than that of theelectrode formation portion. By press-holding only the circumferentialend portion of piezoelectric element 50, the oscillation attenuation ofpiezoelectric element 50 can be minimized. Also, the liquid reagentsupplied to the no-electrode formation plane of piezoelectric element 50flows outside piezoelectric element 50, so that corrosion, deformation,discolor or the like inside the atomizer can be prevented by thewaterproof packing.

A liquid sense circuit substrate 70 is arranged beneath the electrodeformation plane of piezoelectric element 50. Liquid sense circuitsubstrate 70 is electrically connected with comb-type electrodes 51 and52 and liquid sense electrodes 55 and 56 of piezoelectric element 50through a conductive coil spring (resilient body) 71. Liquid sensecircuit substrate 70 is mounted with a circuit that senses theabsence/presence of liquid according to a signal from liquid senseelectrodes 55 and 56. Coil spring 71 is inserted into a hollow shaft 72a of a support panel 72.

By the above structure, the distance from liquid sense electrodes 55 and56 of piezoelectric element 50 from liquid sense circuit substrate 70 isminimized to reduce the influence of disturbance noise (mainly noisecaused by vibration drive oscillation signal). Also, the electrostaticcapacity of the electrical connection between liquid sense electrodes 55and 56 and liquid sensor circuit substrate 70 can be reduced to improvethe S/N. More specifically, the electrostatic capacity causing a changein liquid sense electrodes 55 and 56 is approximately several pF sincethe liquid reagent is in contact and spreads at the backside plane(no-electrode formation plane) of liquid sense electrodes 55 and 56.This change is sensed by liquid sense circuit substrate 70. The usage ofa conductive coil spring 71 ensures the contact between electrodes 51,52, 55 and 56 and liquid sense circuit substrate 70 while minimizing thevibration attenuation of piezoelectric element 50 caused by contact withelectrodes 51, 52, 55 and 56.

The oscillation operation of piezoelectric element 50 will be describedhereinafter. Upon conducting an alternating current of frequency 6 MHz,for example, across electrodes 51 and 52 of piezoelectric element 50, asurface wave propagating at the surface (resilient surface wave) 60 anda bulk wave 61 that travels through the interior are generated. In otherwords, the electrical energy of piezoelectric element 50 is convertedinto oscillation energy. More specifically, electrodes 51 and 52 convertthe electrical energy into mechanical oscillation energy.

In piezoelectric element 50, the oscillation source of piezoelectricelement 50 is comb-type electrodes 51 and 52 formed alternately withrespect to each other. The generated vibratory waves are a surface wave60 and a bulk wave 61. As shown in FIG. 17, bulk wave 61 travels insidepiezoelectric element 50 obliquely with respect to the longitudinaldirection of piezoelectric element 50. When the direction of the normalline of the equiphase surface of the excited bulk wave is θ, θ isrepresented by the following equation. The advancing direction of thebulk wave depends upon the frequency.

θ=sin⁻¹(Vb/P·f)

where Vb is the phase speed of the bulk wave, P is the pitch ofcomb-type electrodes 51 and 52, and f is the frequency.

The bulk wave is propagated while being reflected at the boundary planeof piezoelectric element 50. The oscillation frequency of the excitedsurface wave at comb-type electrodes 51 and 52 is determined mainly bythe sound speed Vs of the surface wave and pitch P. The oscillationfrequency of the bulk wave is determined by the thickness t ofpiezoelectric element 50.

When the oscillation frequency of the surface wave approximates theoscillation frequency of the bulk wave, there is the case where thefrequency is not stable to cause piezoelectric element 50 operate at theoscillation frequency of the surface wave or of the bulk wave inresponse to a slight change in the oscillation load. The structure ofthe oscillation circuit becomes complicated to prevent this event. It istherefore important to select thickness t of piezoelectric element 50 sothat the oscillation frequency of the bulk wave differs from theoscillation frequency of the surface wave.

The bulk wave and the surface wave are reflected at both end portionscrossing the wave propagation direction to cause wave interference. Thisis not desirable from the standpoint of vibration stability. It ispreferable to set the two end portions crossing the wave propagationdirection asymmetric or at least the side face of the end portionnonplanar. Examples thereof are indicated in FIGS. 18A, 18B, 18C andFIGS. 19A, 19B and 19C. FIG. 18A shows an example of a taperedno-electrode formation portion 53 a of piezoelectric element 50. FIG.18B shows an arc-shaped no-electrode formation portion 53 b. FIG. 18Cshows a waveform no-electrode formation portion 53 c. Theseconfigurations cancel the reflection of surface wave 60 or bulk wave 61of FIG. 16 to eliminate vibratory wave interference. Thus, oscillationbecomes stable.

In addition to altering the configurations of no-electrode formationportions 53 a-53 c of piezoelectric element 50, the end plane ofno-electrode formation portion 53 can be set nonplanar as shown in FIGS.19A, 19B and 19C. FIG. 19A shows a saw tooth end plane 54 a. FIG. 19Bshows an end plane 54 b with one stepped side. FIG. 19C shows an endplane 54 c with both stepped sides. Similarly in this case, reflectionof surface wave 60 or bulk wave 61 can be cancelled. The configurationof end planes 54 a-54 c may be incorporated, not only at the end planeof no-electrode formation portion 53, but also at the end plane portionat the side opposite to no-electrode formation portion 53 (the portionwhere electrodes 51 and 52 are formed). Alternatively, theseconfigurations can be provided over the entire end plane ofpiezoelectric element 50. Also, the configurations of no-electrodeformation portions 53 a-53 c in FIGS. 18A, 18B and 18C can be combinedwith the configurations of end planes 54 a-54 c in FIGS. 19A, 19B and19C.

At upper case 31 of atomize unit 30 at main unit cover 10 in FIG. 4(also refer to FIGS. 6A and 6B), an operation display LED 80 and avoltage monitor display LED 81 are provided. LEDs 80 and 81 are arrangedin a direction substantially identical to the spray out direction frommain unit cover 10 (the direction perpendicular to mesh memory 40) in aviewable manner. Operation display LED 80 is lit when operation switch 9is turned on. Voltage monitor display LED 80 is lit when the remainingbattery is low. Accordingly, the conductive state and whether thebattery is low or not can be confirmed visually by the lights of LEDs 80and 81 turned on or off during inhalation. In FIGS. 5, 6A and 6B, acontrol circuit substrate 85 to control the ON/OFF of solenoid 26 isarranged vertically in main unit case 1.

The present atomizer includes a formed component constituting the mainbody of the apparatus such as main unit case 1, cover 2, and main unitcover 10, and another formed component fitted to such components.Packing to ensure waterproof ability at the fitted portion is integrallyformed to one or both of the formed components. More specifically, inFIG. 5, packing 90 is integrally formed at the fitting portion betweenmain unit case 1 and main unit cover 10, and packing 91 is integrallyformed at the fitting portion with the battery storage unit at the lowerportion of main unit case 1. Accordingly, the waterproof reliability isimproved as well as the assembly property.

According to the present embodiment, the comb-type electrodes areprovided only at one side of the piezoelectric element. However, thecomb-type electrode can be provided at both sides of the piezoelectricelement. Such an example is shown in FIG. 20. Referring to FIG. 20,comb-type electrodes 5la, 52 a, 51 b and 52 b are provided at both sidesof piezoelectric element 50. In this case, the comb-type electrodes arearranged so that the phase of the vibratory wave (bulk wave) generatedby the comb-type electrodes provided at both sides is maximizedaccording to wave mechanics.

As a result, an oscillation greater than that where only one side isprovided with the comb-type electrodes can be obtained.

Atomization of the present atomizer will be described with reference toFIG. 21 (enlarged sectional view of the main part). By conducting analternating current across electrodes 51 and 52 of piezoelectric element50, surface wave 60 out of surface wave 60 and bulk wave 61 generated atpiezoelectric element 50 (refer to FIG. 16) is canceled by virtue of theconfiguration of no-electrode formation portions 53-53 c shown in FIGS.18A, 18B and 18C and the configuration of end planes 54 a-54 c shown inFIGS. 19A, 19B and 19C. Only bulk wave 61 is propagated to mesh member40, whereby mesh member 40 vibrates. The plurality of small holes 41 inmesh member 40 shown herein are of a stepped type horn configurationhaving an opening of a large diameter at the side of piezoelectricelement 50 and an opening of a small diameter at the opposite side.

Liquid L is present between piezoelectric element 50 and mesh member 40.The oscillation energy of piezoelectric element 50 is propagated toliquid L, which in turn is propagated to mesh member 40. By thevibration of mesh member 40, liquid L is diffused from small hole 41 ofmesh member 40 as atomized particles L′. In order to increase theamplitude displacement of the ultrasonic vibration to improve theatomization efficiency, the cross sectional shape of small hole 41corresponds to an ultrasonic horn shape that is determined by theultrasonic oscillation frequency and the sound speed of the liquid. Asan example thereof, the cross section of small hole 41 corresponds to astepped type horn configuration. Assuming that the sound speed of sprayliquid (spray particle L′) is 1500 m/s, the ultrasonic oscillationfrequency is 6 MHz, the wavelength is λ, the amplitude enlargement rateof (D/d) 2 is obtained by setting step position h to 62.5 μm equal toλ/4 to obtain atomization of favorable efficiency with a relatively lowpower.

More specifically, mesh member 40 exhibits the highest atomizationefficiency by the following conditions.

h=λ/4, λ=v/f

h: inlet hole depth of small hole 41

v: sound speed of liquid reagent

λ: wavelength

f: oscillation frequency

s·(D/d)2

s: amplification rate

D: inlet hole diameter of small hole 41

d: outlet hole diameter of small hole 41

The cross sectional configuration of small hole 41 may be the horn shapeof a conical type, a catenoidal or exponential type.

The cases corresponding to a small hole 41 of the conical type andexponential type horn configuration will be described hereinafter.

FIGS. 22A and 22B show conical type and exponential type horn-shapedsmall holes 41 a and 41 b, respectively. In the drawings, A1 and A2represent the cross sectional area at the end plane of each type and lrepresents the depth of small hole 41.

In FIG. 22A, the frequency equation is represented as below.$\begin{matrix}{{\tan \quad k^{\prime}l} = \frac{( {\beta - 1} )^{2}k^{\prime}l}{{( {k^{\prime}l} )^{2}\beta} + ( {\beta - 1} )^{2}}} \\{k^{\prime} = {\frac{2\quad \pi \quad f}{\upsilon}:{f\quad {is}\quad {frequency}}}} \\{\beta = {\sqrt{\frac{A2}{A1}}:{\upsilon \quad {is}\quad {sound}\quad {speed}}}}\end{matrix}$

Referring to FIG. 22B, the cross sectional area Ax at a distance x fromend plane A1 is represented by the following equation.

Ax=Ale ^(hx)

where h is a taper constant.

In this case, the frequency equation is represented as below.$\begin{matrix}{\quad {{k^{\prime}l} = \frac{\pi}{q}}} \\{k^{\prime} = \frac{2\quad \pi \quad f}{\upsilon}} \\{q = \sqrt{1 - P^{2}}} \\{p = \frac{h}{2k^{\prime}}}\end{matrix}$

By any of the above horn configurations, the amplification rate andamount of atomization are greater than those of the conventionalstraight shape (straight round hole) or a reticulated hole. In otherwords, atomization of favorable efficiency is realized.

As shown in FIGS. 1-3, a projection 1 ais present at the rear of theupper portion of main unit case 1 when the present atomizer is used.Since operation switch 9 is provided at a front face opposite toprojection 1 a(taking into account the human engineering nature),operation switch 9 can be operated with main unit case 1 graspednaturally. Since main unit case 1 can be grasped with a natural grip,the possibility of main unit case 1 being dropped during handling islow.

Since the present atomizer has liquid reagent bottle 20 and atomize unit30 formed integrally at main unit cover 10 as shown in FIGS. 6A and 6B,piezoelectric element 50 is exposed when upper and lower parts 21 and 22and upper and lower cases 31 and 32 are removed from main unit cover 10.Accordingly, the exposed surface of piezoelectric element 50(no-electrode formation plane) can be easily cleaned with a cotton budor the like. In view of the fact that the exposed surface ofpiezoelectric element 50 is easily contaminated due to the attachmentand drying of liquid reagent and also adherence of dust, maintenance isfacilitated by the above structure.

Liquid reagent bottle 20 (upper and lower parts 21 and 22) and theattachment portion of piezoelectric element 50 are coupled and held withrespect to each other by being attracted by a magnet accommodated in apair of magnet storage units 82 provided opposite at lower part 22.

According to the atomizer of FIG. 5, control circuit substrate 85 and anoscillation circuit substrate (not shown) are arranged in main unit case1 whereas liquid reagent bottle 20, mesh member 40, piezoelectricelement 50 and the like are arranged at main unit cover 10. By providingthe components such as piezoelectric element 50 that have thepossibility of being damaged by erroneous handling in the form ofmodular components of main unit cover 10, maintenance is improved byremoving main unit cover 10 from main unit case 1. For example, mainunit cover 1 or each substrate in main unit case 1, when damaged, can beeasily exchanged. As to the spray mechanism portion (mesh member 40 andthe like) required for critical adjustment, the accuracy can bemaintained since they are provided as modular components that cannot beeasily detached. Thus, assembly thereof is improved.

Industrial Applicability

According to the atomizer of the present invention, a piezoelectricelement with comb-type electrodes having electrodes formed alternatelyis combined with a mesh member, wherein a bulk wave traveling within thepiezoelectric element is used as the vibratory wave, not the surfacewave propagating at the surface defined by the comb-type electrode pitchof the piezoelectric element. Therefore, stable atomization withfavorable spray out efficiency is obtained.

What is claimed is:
 1. An atomizer comprising: a piezoelectric elementincluding comb-type electrodes having one electrode and anotherelectrode formed alternately, oscillation means driving saidpiezoelectric element, a mesh member including many small holes arrangedin close proximity to said piezoelectric element, a reservoir storing aliquid, and liquid supply means for supplying the liquid in saidreservoir between said piezoelectric element and said mesh member,wherein a vibratory wave of said piezoelectric element used foratomization by said oscillation means is mainly a wave traveling withinthe piezoelectric element.
 2. The atomizer according to claim 1, whereinsaid piezoelectric element is of a material of lithium niobate, and hasa 41±15° rotation Y cut and Y axis projection propagation direction. 3.The atomizer according to claim 1, wherein said piezoelectric elementhas a thickness so that an oscillation frequency of a surface wave andthe oscillation frequency of a bulk wave differ from each other.
 4. Theatomizer according to claim 1, wherein comb-type electrodes of saidpiezoelectric element are arranged so that an oscillation frequency of asurface wave differs from the oscillation frequency of a bulk wave. 5.The atomizer according to claim 1, wherein an end portion of saidpiezoelectric element crossing at least an advancing direction of asurface wave is of a configuration that does not cause interferencebetween a wave reflected at the end portion and said surface wave. 6.The atomizer according to claim 5, wherein the configuration that doesnot cause interference between said wave reflected at an end portion andsaid surface wave have both end planes asymmetric/or having at least theend plane of one said end portion nonplanar.
 7. The atomizer accordingto claim 1, wherein said piezoelectric element has two opposite planes,said comb-type electrode being provided only at one plane side of saidpiezoelectric element.
 8. The atomizer according to claim 7, whereinsaid comb electrode is provided at a plane opposite to the plane facingsaid member.
 9. The atomizer according to claim 7, wherein saidpiezoelectric element includes a liquid detection electrode detectingabsence/presence of said liquid, provided adjacent to one side of saidcomb-type electrode.
 10. The atomizer according to claim 1, wherein thevibratory wave used for said atomization is formed and generated by saidpiezoelectric element formed to reduce effect by a surface wavetraveling through a surface of said piezoelectric element.
 11. Theatomizer according to claim 1, wherein a cross sectional configurationof said small hole is of a horn configuration determined by anultrasonic vibration frequency and a sound speed of said liquid.
 12. Anatomizer comprising a piezoelectric element including comb-typeelectrodes having one electrode and another electrode formedalternately, oscillation means driving said piezoelectric element, amesh member including many small holes arranged in close proximity tosaid piezoelectric element, a reservoir storing a liquid, and liquidsupply means for supplying the liquid in said reservoir between saidpiezoelectric element and said mesh member, wherein a cross sectionalconfiguration of the small hole of said mesh member is of a hornconfiguration formed according to an oscillation frequency of thepiezoelectric element and a sound speed of the liquid.
 13. An atomizercomprising a piezoelectric element including comb-type electrodes havingone electrode and another electrode formed alternately, oscillationmeans driving said piezoelectric element, a mesh member including manysmall holes arranged in close proximity to said piezoelectric element, areservoir storing a liquid, and liquid supply means supplying the liquidin said reservoir between said piezoelectric element and said meshmember, wherein said piezoelectric element and mesh member are arrangedso that their facing planes cross at an acute angle, and the liquid fromthe liquid supply means is supplied from an opening side therebetween.14. An atomizer comprising a piezoelectric element including comb-typeelectrodes having one electrode and another electrode formedalternately, oscillation means driving said piezoelectric element, amesh member including many small holes arranged in close proximity tosaid piezoelectric element, a reservoir storing a liquid, and liquidsupply means supplying the liquid in said reservoir between saidpiezoelectric element and said mesh member, wherein said piezoelectricelement and said mesh member are arranged so that their facing planescross at an acute angle, and said reservoir includes a liquid supplypipe extending to an opening side between said piezoelectric element andmesh member.
 15. An atomizer comprising a piezoelectric elementincluding comb-type electrodes having one electrode and anotherelectrode formed alternately, oscillation means driving saidpiezoelectric element, a mesh member including many small holes arrangedin close proximity to said piezoelectric element, a reservoir storing aliquid, and liquid supply means supplying the liquid in said reservoirbetween said piezoelectric element and said mesh member, wherein saidpiezoelectric element includes a liquid sense electrode sensing liquidfrom the reservoir at a comb-type electrode formation plane, a liquidsense circuit substrate sensing absence/presence of liquid according toa signal from the liquid sense electrode is provided, the liquid sensecircuit substrate arranged below the comb-type electrode formation planeof the piezoelectric element, and the liquid sense electrode of thepiezoelectric element and the liquid sense circuit substrate areelectrically connected by a conductive resilient body.
 16. An atomizercomprising a piezoelectric element including comb-type electrodes havingone electrode and another electrode formed alternately, oscillationmeans driving said piezoelectric element, a mesh member including manysmall holes arranged in close proximity to said piezoelectric element, areservoir storing a liquid, and liquid supply means supplying the liquidin said reservoir between said piezoelectric element and said meshmember, wherein said liquid supply means supplies the liquid in saidreservoir by urge-operating a diaphragm.
 17. An atomizer comprising apiezoelectric element including comb-type electrodes having oneelectrode and another electrode formed alternately, oscillation meansdriving the piezoelectric element, a mesh member including many smallholes arranged in close proximity to the piezoelectric element, areservoir storing the liquid, liquid supply means supplying the liquidin the reservoir between the piezoelectric element and the mesh member,and liquid amount sense means sensing an amount of liquid on thepiezoelectric element, wherein said liquid supply means supplies theliquid in the reservoir by urge-operating a diaphragm, and theurge-operation of the diaphragm is controlled according to an output ofsaid liquid amount sense means.
 18. An atomizer comprising apiezoelectric element including comb-type electrodes having oneelectrode and another electrode formed alternately, oscillation meansdriving the piezoelectric element, a mesh member including many smallholes arranged in close proximity to the piezoelectric element, areservoir storing the liquid, liquid supply means supplying liquid inthe reservoir between the piezoelectric element and the mesh member, anda mesh member case holding the mesh member, wherein said mesh membercase is formed of metal or ceramic.